Derivatives of quinolinecarboxylic acids

ABSTRACT

Quinolinecarboxylic acid derivatives of the formula: ##STR1## where R 1  and R 2  are identical or different and each is independently of the other hydrogen or halogen, 
     R 3  is C 1  -C 13  -alkoxy, C 1  -C 8  -monoalkylamino or di(C 1  -C 8  alkyl)amino and 
     R 4  and R 5  are identical or different and each is independently of the other hydrogen, C 1  -C 13  -alkyl or C 1  -C 13  -alkoxy, 
     with the proviso that R 3  is not methoxy or ethoxy when at the same time R 1 , R 2 , R 4  and R 5  are each hydrogen, are useful as color formers for preparing pressure-sensitive papers.

The present invention relates to novel quinolinecarboxylic acidderivatives of the formula I ##STR2## where R¹ and R² are identical ordifferent and each is independently of the other hydrogen or halogen,

R³ is C₁ -C₁₃ -alkoxy, C₁ -C₈ -monoalkylamino or di(C₁ -C₈ -alkyl)aminoand

R⁴ and R⁵ are identical or different and each is independently of theother hydrogen, C₁ -C₁₃ -alkyl or C₁ -C₁₃ -alkoxy,

with the proviso that R³ is not methoxy or ethoxy when at the same timeR¹, R², R⁴ and R⁵ are each hydrogen, and to the use ofquinolinecarboxylic acid derivatives as color formers for preparingpressure-sensitive recording papers.

DE-A-440 008 discloses the methyl and ethyl esters of2-styrylquinoline-4-carboxylic acid and uses them as intermediates orstarting materials for the preparation of 4-aminoquinoline derivativeswhich are useful as bactericides. These compounds are also described inChem. Heterocycl. Comp. Vol. 24 (1988), 670. Nothing is said about useas color former.

DE-A-3 405 395 discloses quinoline-based color formers. These colorformers are 2-styrylquinoline derivatives which have no substituents inring position 4 of the quinoline ring.

Moreover, EP-A-339 518 and EP-A-384 313 describe quinoline derivativeswhich have a substituted phenyl group in ring position 2 and can be usedas color formers. However, it has been found that the prior art productsstill have application defects.

It is an object of the present invention to provide novelquinolinecarboxylic acid derivatives which have advantageous applicationproperties.

We have found that this object is achieved by the quinolinecarboxylicacid derivatives of the formula I defined at the beginning.

Any alkyl appearing in the abovementioned formula I may be eitherstraight-chain or branched.

R¹ and R² are for example fluorine, chlorine or bromine.

R⁴ and R⁵ are for example methyl, ethyl, propyl, isopropyl, butyl,isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl,tert-pentyl, hexyl, 2-methylpentyl, heptyl, octyl, 2-ethylhexyl,isooctyl, nonyl, isononyl, decyl, isodecyl, undecyl, dodecyl, tridecylor isotridecyl. (The terms isooctyl, isononyl, isodecyl and isotridecylare trivial names derived from the oxo process alcohols (cf. UllmannsEncyclopadie der technischen Chemie, 4th edition, volume 7, pages 215 to217, and volume 11, pages 435 and 436.)

R⁴ and R⁵ may also be for example, like R³, methoxy, ethoxy, propoxy,isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy,isopentyloxy, neopentyloxy, tert-pentyloxy, hexyloxy, 2-methylpentyloxy,heptyloxy, octyloxy, 2-ethylhexyloxy, isooctyloxy, nonyloxy,isononyloxy, decyloxy, isodecyloxy, undecyloxy, dodecyloxy, tridecyloxyor isotridecyloxy.

R³ may also be for example mono- or dimethylamino, mono- ordimethylamino, mono- or dipropylamino, mono- or diisopropylamino, mono-or dibutylamino, mono- or diisobutylamino, mono- or di(sec-butyl)amino,mono- or dipentylamino, mono- or diisopentylamino, mono- ordineopentylamino, mono- or dihexylamino, mono- or diheptylamino, mono-or dioctylamino, mono- or diisooctylamino, mono- ordi(2-ethylhexyl)amino, mono- or dinonylamino, mono- or diisononylamino,mono- or didecylamino, mono- or diisodecylamino, mono- ordiundecylamino, mono- or didodecylamino, mono- or ditridecylamino ormono- or diisotridecylamino.

Preference is given to quinolinecarboxylic acid derivatives of theformula I where

R¹ and R² are each independently of the other hydrogen or chlorine,

R³ is C₁ -C₈ -alkoxy, C₁ -C₄ -monoalkylamino or di(C₁ -C₄ -alkyl)amino,and

R⁴ and R⁵ are each independently of the other hydrogen or C₁ -C₄-alkoxy.

Particular preference is given to quinolinecarboxylic acid derivativesof the formula I where

R¹ and R² are each hydrogen,

R³ is C₁ -C₈ -alkoxy, C₁ -C₄ -monoalkylamino or di(C₁ -C₄ -alkyl)aminoand

R⁴ and R⁵ are each independently of the other C₁ -C₄ -alkoxy, or one ofR⁴ and R⁵ may also be hydrogen.

The novel quinoline derivatives of the formula I can be obtained in aconventional manner, for example as described in Chem. Heterocycl. Comp.Vol. 24 (1988), 670.

For example, isatins of the formula II ##STR3## Where R¹ and R² are eachas defined above, can be converted with acetone in the presence of abase in 2-methylquinolinecarboxylic acids of the formula III ##STR4##where R¹ and R² are each as defined above.

By condensing benzaldehydes of the formula IV ##STR5## where R⁴ and R⁵are each as defined above, with the methylquinolinecarboxylic acids IIIin an acid medium it is possible to arrive at thestyrylquinolinecarboxylic acids of the formula V ##STR6## where R¹, R²,R⁴ and R⁵ are each as defined above. They can then be for exampleconverted into the corresponding carbonyl halides and reacted withcompounds of the formula VI

    R.sup.3 --H                                                (VI)

where R³ is as defined above, to give the quinolinecarboxylic acidderivatives of the formula I.

The present invention further provides for the use ofquinolinecarboxylic acid derivatives of the formula Ia ##STR7## where R¹and R² are identical or different and each is independently of the otherhydrogen or halogen,

R³ is C₁ -C₁₃ -alkoxy, C₁ -C₈ -monoalkylamino or di(C₁ -C₈ -alkyl)aminoand

R⁴ and R⁵ are identical or different and each is independently of theother hydrogen, C₁ -C₁₃ -alkyl or C₁ -C₁₃ -alkoxy,

as a color former for preparing pressure-sensitive recording papers.

The quinolinecarboxylic acid derivatives of the formula Ia are slightlycolored or colorless compounds whose solutions in inert organic solventsproduce on contact with electron acceptors colorings in greenish yellowto reddish orange shades, depending on the substitution pattern of thequinolinecarboxylic acid derivative. Examples of electron acceptorsubstances are carboxylic or mineral acids, kaolin, bentonite, activatedclay, aluminum silicate, attapulgite or any other desired clay, acidicpolymeric materials, such as condensation products based on phenolsand/or phenolsulfonic acids, also metal oxides or salts, such as zincoxide, aluminum oxide, zinc chloride, iron stearate or cobaltnaphthenate.

Owing to these properties, the compounds of the formula Ia are suitablefor use as color formers in pressure-sensitive recording materials.

For use in pressure-sensitive systems, the quinolinecarboxylic acidderivatives Ia are advantageously microencapsulated in the form ofsolutions in organic solvents, for example chloroparaffins, partiallyhydrogenated biphenyl or terphenyl, alkylbenzenes, alkylnaphthalenes,alkylated dibenzylbenzenes, paraffin oil, mineral oil or else customarylow-boiling solvents, such as xylene or toluene, and applied inmicroencapsulated form to the base material, for example paper. On theapplication of pressure, contact with electron acceptors will thenresult in color formation in the area where the pressure was applied.

Suitable processes for preparing microcapsules are known for examplefrom US-A-2 800 457, US-A-2 800 458, DE-A-2 119 933 or EP-A-26 914. Itis also possible to disperse the compounds of the present invention bythe process described in US-A-3 103 404 in wax or oil-wax mixtures andto use these mixtures to coat base materials, such as foils or paper.Pressure-sensitive materials are obtained which are suitable for copyingonto electron acceptor coated substances and which after use are removedlike carbon paper.

The Examples which follow will further illustrate the invention.

EXAMPLE 1 Stage 1: 2-Methylquinoline-4-carboxylic acid

287 g (1.6 mol) of moist isatin (dry matter content: 82% by weight) weresuspended in 2000 ml of 38% strength by weight sodium hydroxidesolution, admixed with 25.4 g (0.64 mol) of sodium hydroxide and 1.1 gof wetting agent, and heated to 50° C. At that temperature 93 g (1.6mol) acetone were added over 15 minutes. The mixture was subsequentlystirred at 50° C. for 3 hours and then cooled down to 25° C, and thesolid product was filtered off with suction. After washing with 33%strength by weight sodium hydroxide solution the residue was dissolvedin 2.5 1 of water, reprecipitated with 30% strength by weighthydrochloric acid at pH 2, filtered off with suction and washed withwater acidified with hydrochloric acid (pH 2).

Drying at 60° C. left 219 g (73%) of 2-methyl-quinoline-4-carboxylicacid of melting point 247-249° C. Stage 2:2-(4-Methoxystyryl)quinoline-4-carboxylic acid

150 g (0.8 mol) of 2-methylquinoline-4-carboxylic acid and 110 g (0.8mol) of p-methoxybenzaldehyde were heated at the boil in 300 ml ofglacial acetic acid for 6 hours during which 73 g of glacial acetic acidwere distilled off at the same time. The carboxylic acid was isolatedand purified by filtering off with suction and washing with glacialacetic acid and methanol. Drying left 144 g (59%) of2-(4-methoxystyryl)quinoline-4-carboxylic acid of melting point 284-286°C. Stage 3: Methyl 2-(4-methoxystyryl)quinoline-4-carboxylate

12.3 g (0.04 mol) of 2-(4-methoxystyryl)quinoline-4-carboxylic acid in50 ml of thionyl chloride and 1 ml of pyridine were heated at 30° C. for90 minutes and then at 60° C. for a further 15 minutes. The excessthionyl chloride was removed under reduced pressure, and the acidchloride was converted with 150 ml of methanol into the methyl ester of2-(4-methoxystyryl)quinoline-4-carboxylic acid. After standing at roomtemperature for 12 hours, the product, which had precipitated in theform of a hydrochloride, was filtered off with suction and washed withmethanol. The base was liberated by suspending and stirring the crudeproduct in aqueous bicarbonate solution until the initially red materialturned yellow.

The yield of methyl 2-(4-methoxystyryl)quinoline-4-carboxylate of theformula ##STR8## after filtering off with suction while washing untilneutral and drying was 7.2 g (56%).

Melting point 99.5° C.

λ_(max) (measured in dichloromethane): 373 nm.

λ_(max) (measured in methanol, containing 2% by weight of hydrogenchloride): 432 nm.

EXAMPLE 2

2-(4-Methoxystyryl)quinoline-4-N,N-di-n-butylcarboxamide

12.3 g (0.04 mol) of 2-(4-methoxystyryl)quinoline-4-carboxylic acid (seeExample 1) were dissolved in 50 ml of thionyl chloride by stirring atnot more than 30° C. and admixed with 1 ml of pyridine. After 1.75 hoursthe excess thionyl chloride was removed under reduced pressure and theresidue was admixed with 150 ml of di-n-butylamine while cooling withice, and the reaction temperature rose to 80° C. The reaction mixturewas stirred at room temperature for a further 12 hours and was thenpoured into 500 ml of water. The organic phase was purified by stirringout with 5% strength by weight hydrochloric acid and filtering theresulting residue off with suction. For further purification, theresidue was taken up in toluene and then washed with 5% strength byweight hydrochloric acid and dilute sodium hydroxide solution.

The oil resulting on drying over sodium sulfate and removing the solventwas purified by filtration through silica gel with 4:1 (v/v)toluene/ethyl acetate. Crystallization with cyclohexane gave 4.6 g (27%)of 2-(4-methoxystyryl)quinoline-4-N,N-di-n-butylcarboxamide of theformula ##STR9## of melting point 77° C.

λ_(max) (measured in dichloromethane): 362 nm.

λ_(max) (measured in methanol, containing 2% by weight of hydrogenchloride): 420 nm.

The procedures described in Examples 1 and 2 were also used to obtainedthe quinolines of the formula ##STR10## listed in the following Table:

                                      TABLE                                       __________________________________________________________________________                                 m.p.                                                                             λ max*.sup.)                                                                λ max**.sup.)                     No. R.sup.1                                                                          R.sup.2                                                                          R.sup.3                                                                              R.sup.4                                                                            R.sup.5                                                                              [°C.]                                                                     [nm] [nm]                                     __________________________________________________________________________     3  H  H  OCH.sub.3                                                                            3-OCH.sub.3                                                                        4-OCH.sub.3                                                                          133                                                                              377  445                                       4  H  H  N(C.sub.4 H.sub.9).sub.2                                                             3-OCH.sub.3                                                                        4-OCH.sub.3                                                                          ol 367  432                                       5  H  H  OCH.sub.3                                                                            H    4-CH.sub.3                                                                           119                                                                              364  408                                       6  4-Cl                                                                             4-Cl                                                                             OCH.sub.3                                                                            H    4-OCH.sub.3                                                                          156                                                                              365  407                                       7  H  H  O--nC.sub.4 H.sub.9                                                                  H    4-OCH.sub.3                                                                           90                                                                              372  432                                       8  H  H  O--nC.sub.4 H.sub.9                                                                  H    H       42                                                                              359  395                                       9  H  H  O--nC.sub.4 H.sub.9                                                                  H    4-nOC.sub.4 H.sub.9                                                                   81                                                                              374  436                                      10  H  H  O--nC.sub.8 H.sub.17                                                                 H    4-OCH.sub.3                                                                           59                                                                              372  432                                      11  H  H  O--nC.sub.4 H.sub.9                                                                  H    2-nOC.sub.4 H.sub.9                                                                   56                                                                              367  424                                      12  H  H  N--nC.sub.8 H.sub. 17                                                                H    4-OCH.sub.3                                                                          131                                                                              377  415                                      13  H  H  O--nC.sub.4 H.sub.9                                                                  3-OCH.sub.3                                                                        4-OCH.sub.3                                                                          111                                                                              379  439                                      14  H  H  O--nC.sub.6 H.sub.13                                                                 3-OCH.sub.3                                                                        4-OCH.sub.3                                                                          105                                                                              381  435                                      15  H  H  O--nC.sub.8 H.sub.17                                                                 3-OCH.sub.3                                                                        4-OCH.sub.3                                                                          101                                                                              392  439                                      16  H  H  N--nC.sub.8 H.sub.17                                                                 3-OCH.sub.3                                                                        4-OCH.sub.3                                                                          151                                                                              385  430                                      17  H  H  O--CH.sub.3                                                                          2-OCH.sub.3                                                                        4-OCH.sub.3                                                                          130                                                                              372  438                                      __________________________________________________________________________     *.sup.) measured in dichloromethane                                           **.sup.) measured in methanol containing 2% by weight of hydrogen chlorid                                                                              

EXAMPLE 18 (Use)

A 0.5% strength by weight solution of the quinolinecarboxylic acidderivative of Example 3 in diisopropylnaphthalene was applied with a 6μm draw bar to a CF paper from wiggins Teape. A yellow color developed,whose K/S value (color strength) was determined by the CIELAB system.After one hour's exposure in the Suntest instrument from Hanau, the ΔEvalue (light fastness) was determined, again in accordance with CIELAB.

K/S: 2,0, ΔE: 6.

EXAMPLE 19 (Use)

Example 18 was repeated with the quinolinecarboxylic acid derivative ofExample 1.

K/S: 2.4, ΔE: 8.

We claim:
 1. A quinolinecarboxylic acid derivative of the formula I##STR11## where R¹ and R² are identical or different and each isindependently of the other hydrogen or halogen,R³ is C₁ -C₁₃ -alkoxy, C₁-C₁₃ -monoalkylamino or di(C -C₁ -C₈ -alkyl)amino and R⁴ and R⁵ areidentical or different and each is independently of the other hydrogen,C₁ -C₁₃ -alkyl or C₁ -C₁₃ -alkoxy,with the proviso that R³ is notmethoxy or ethoxy when at the same time R¹, R², R⁴ and R⁵ are eachhydrogen.
 2. A quinolinecarboxylic acid derivative as claimed in claim1, whereinR¹ and R² are each independently of the other hydrogen orchlorine, R³ is C₁ -C₁₃ -alkoxy, C₁ -C₄ -monoalkylamino or di(C₁ -C₄-alkyl)amino, and R⁴ and R⁵ are each independently of the other hydrogenor C₁ -C₄ -alkoxy.
 3. A quinolinecarboxylic acid derivative of theformula I ##STR12## where R¹ and R² are identical or different and eachis independently of the other hydrogen or halogen,R³ is C₁ -C₁₃ -alkoxy,C₁ -C₈ -monoalkylamino or di(C₁ -C₈ -alkyl)amino and R⁴ and R⁵ areidentical or different and each is independently of the other hydrogenor C₁ -C₁₃ -alkoxy, with the proviso that either R⁴ or R⁵ must be C₁-C₁₃ -alkoxy.